People with MS are often aware of the JCVirus and the risk it poses for PML, the brain infection that causes severe disabilities and death. Could it be that the blood test for this virus is insufficient in determining the risk of taking Tysabri?

Our blood works in mysterious ways! Turns out certain stem cells will become B-cell lymphocytes. These cells are susceptible to the JCVirus. Once the white cells are infected they carry the PML infection to the brain. Patients on Tysabri have 3-10 times the number of B-cell lymphocytes.

Many patients feel they can go beyond the recommended two-year limit on Tysabri because they are tested for the JCVirus every six months. Is that test truly effective? Maybe not. Researchers state on WebMD, “Perhaps most concerning, 10 study participants had evidence of the JC virus in their blood but tested negative for antibodies to it.” This means some patients could be at higher risk of developing PML than they think. The current practice of the JCVirus test may be insufficient in determining the risks.

For more information read, http://www.webmd.com/multiple-sclerosis/news/20140325/new-clues-to-link-between-ms-drug-tysabri-and-rare-brain-disease?page=2. Images from: www.sanidadanimal.info and reasonablywell-julia.blogspot.com.